"What's the deal with GSM? I see it on every product page but no one explains it."

Fair question, and I get it—it's one of those numbers that gets thrown around like it's obvious. GSM stands for grams per square meter. It's a measure of how heavy the fabric is per square meter. Simple as that. But here's the thing: heavier doesn't automatically mean better. It's about what you need.

For a California office commuter, that means thinking about your day. Are you biking in at 8 AM with the sun already baking? Or are you walking from a parking garage to an AC'd lobby? Your answer changes which weight makes sense.